Perspectives on Fuel Quality

The importance of biodiesel fuel quality was hammered upon at the 2006 National Biodiesel Conference and throughout the past year. With the National Renewable Energy Laboratory's unsettling quality results fresh in people's minds, concerns over the condition of U.S. biodiesel supplies are mounting. Here's what the experts are saying about the state of quality in this industry today and what can be done to improve it.
By Ron Kotrba | January 24, 2007
When the National Renewable Energy Laboratory (NREL) publicized the results of its biodiesel fuel quality report revealing that half of 32 samples collected nationally over the course of 2006 failed to fully conform to the ASTM D 6751 specification for B100, concerns began to surface regarding how damaging those findings might be for individual producers-and the entire industry. Transparency, however, is critical during times like these. As NREL began releasing those troublesome findings in October, Biodiesel Magazine published a story about increasing occurrences of biodiesel storage tanks and fuel filters loading with deposits. Many experts say the conglomeration of impurities in B100-traces of mono- and diglycerides, in the presence of certain sterols found more concentrated in some feedstocks than others-is one of the industry's greatest concerns now. Like cholesterols in the body, other sterols have similar "attract and collect" effects in the proximity of partially reacted triglycerides left in the finished biodiesel. Cooler temperatures above the cloud point also play a role in the precipitation of these insoluble impurities.

"Beginning in October, we shared these results with the NBB (National Biodiesel Board) and its members, a broad audience of OEMs (original equipment manufacturers), biodiesel distributors and biodiesel researchers," NREL Principle Engineer Robert McCormick says. "From the NBB, the response has been very supportive and coupled with a strong call for enforcement of the quality standards by the [Internal Revenue Service, U.S. EPA] and by state agencies." He says the petroleum companies and OEMs were disappointed by the results. "In some sense, I think they recognize this as an unpleasant but normal growing pain in a rapidly growing industry," McCormick tells Biodiesel Magazine. "Many of the representatives of these companies have also begun to question whether or not biodiesel is ready for prime time."

Despite the vigorous pursuit undertaken by the NBB through its biodiesel quality assurance program BQ-9000, quality is obviously still a disconcerting issue. Aside from the need to get more producers and marketers certified through BQ-9000, what else can producers who make biodiesel-and those city and fleet managers and retailers who purchase it-do to help themselves help this industry?

Identifying the Issues
"The biggest quality issue is a producer issue," says Michael Haas, a chemist with the USDA Agricultural Research Service (ARS) and former president of the American Oil Chemists' Society (AOCS). "Producers need to pledge allegiance to quality, or they will kill this industry." As the courier of this predication, Haas isn't worried about the adage of shooting the messenger. "I'll gladly take that bullet," he tells Biodiesel Magazine. "I bet Bob McCormick and Steve Howell (of the NBB) would take that bullet, too."

Working under the direction of McCormick, NREL Engineer Teresa Alleman says that, according to data from those 32 national samples she analyzed, there's one specification in D 6751 that is the most troublesome for U.S. producers to meet. "Clearly the most repeated offense and the most troubling failure is failure to meet the total glycerin requirement," Alleman says. "The failure rate for free glycerin was very low-one sample out of 32-but 10 samples failed on total glycerin. This indicates high levels of bound glycerin." It also indicates incomplete reaction. She stresses that bound glycerin levels can lead to immediate filter problems at "moderately low temperatures."

The past three winters have shown researchers and the biodiesel industry something that they may have underappreciated until recently, with respect to the role of sterol glucosides in biodiesel fuel, Haas says. As a result, NREL has begun to look into this once-neglected aspect of quality control. "ASTM has formed a task force to examine the issue of the formation of precipitates in biodiesel and biodiesel blends after long storage [hours] at cold temperatures above the cloud point," McCormick says. "NREL is taking an active role in this task force."

In sync with his peers, USDA ARS Chemical Engineer Robert Dunn says problems during the winter of 2005-'06 indicate that there needs to be a better understanding of what the biodiesel quality issues really are. "If I had to label one issue as being the most pressing for the industry, I'd have to say it's that of contaminants and their effect on cold flow," says Dunn, who recently returned from an AOCS meeting in Champaign, Ill. "At that meeting, the subject of trace levels of monoglycerides and sterol glucosides causing problems for biodiesel after long periods of storage in unheated tanks was very prominent," he tells Biodiesel Magazine.

Haas lays the onus once again on producers. "The technical people can go to their labs and do all of the research that they want, but until producers feel the need to consistently meet those standards, what would it do?" he says. McCormick emphasizes, however, that some producers and distributors make and deliver quality fuel every day. Nevertheless, two issues that experts believe biodiesel fuel quality ought to revolve around are compelling producers "by carrot or by stick," as Haas says, to consistently meet current specifications as they exist, and evolving those same standards as the need arises.

Program and Research Efforts
"I strongly support the idea of the BQ-9000 program," McCormick says. "Essential requirements of the program include testing of every batch for quality and maintaining records to prove it. How could any company go wrong with this approach?" Some suggest BQ-9000 may be too expensive, but Haas says if it became the industry standard, unaccredited producers would no longer be the "norm" and purchasers would likely dismiss buying fuel without that seal of approval, and what it represents. "The message producers need to hear is that testing fuel is not an option," says Stu Porter, ASTM committee member and BBI Biofuels Canada's biodiesel technical analyst. "Does it cost money? Yes, but if you want to play, those are the rules of engagement."

The AOCS is offering to help develop solutions. "I've long thought that AOCS should have a bigger presence in the biodiesel industry," Haas tells Biodiesel Magazine. Dunn notes that the AOCS's Analytical and Industrial Oil Products divisions are sponsoring an entire session on biodiesel fuel quality at its 2007 annual meeting in Quebec City. "AOCS is looking to contribute its expertise toward fuel quality and the feedstock issue," Dunn says.

ASTM has begun early work with NREL to design a standard to reduce precipitates in fuel. "What we hope will come out of this is an additional performance requirement in ASTM D 6751 that eliminates cold temperature filter plugging issues in biodiesel blends that would not be predicted by a cloud point measurement," McCormick says. Haas says this work may result in some restriction on the amount of sterol glucosides allowable in biodiesel feedstocks. "We may come to see a sterol glucosides component in ASTM," he says. "If the feedstock meets the sterol spec, then the resulting biodiesel will, too." This could resemble Europe's iodine spec, meaning certain feedstocks might not pass muster. The jury is still out on reevaluating the ASTM total glycerin spec, specifically the bound glycerin portion. "That has yet to be determined," Dunn says. A solid step, however, would be getting all producers to meet all the existing quality standards.

Provisional Solutions
Renewable Energy Group Inc. (REG), the biggest player in emerging large-scale turnkey biodiesel plants, filed for a patent on a filtration method being practiced at the plants it designs. Myron Danzer, vice president of customer and technical services at REG, tells Biodiesel Magazine the company hasn't made public this specific measure for quality assurance. While he chose not to give details, some industry experts believe that the fuel is chilled down for a time at temperatures above the cloud point to allow for settling of any precipitates, after which the impurities are filtered out. This procedure is followed by a sampling process. REG may be setting the quality mold for others to replicate.

Upcoming changes to D 6751 will also help to curb the presence of poor-quality biodiesel in the marketplace. According to Porter, in mid-February, ASTM is expected to make official several already-approved changes to D 6751, among which is the first-ever oxidative stability specification-a three-hour Rancimat test. Also, a loophole existing as Footnote No. 1 in D 6751, which has allowed consenting parties to overlook one or more areas in which the biodiesel is off-spec, is being closed. "Under the loophole, there was even an instance where someone was selling vegetable oil as biodiesel," Porter says.

Randall von Wedel, principle chemist of Cytoculture International and inventor of the pHLip Test-a 10-minute field test with striking accuracy-says he encourages hesitant fuel purchasers to stipulate certain provisions in contracts that require rigorous quality control measures. Examples of this include documented sampling of B100 from the top, middle and bottom of the delivery and storage tanks; the right to refuse off-spec product; guaranteed replacement of bad fuel at no cost to the purchaser; and more. "I've lived through the near-death experience of biodiesel," von Wedel says, referencing the city of Berkley, Calif., and its acceptance and subsequent rejection of biodiesel a couple of years ago. "Now, here in California, railcars are quarantined and sampled from the top, middle and bottom, for water and sediment, total glycerin, acid number, and flashpoint." This is done on-site using the the pHLip Test.

"I think the pHLip Test has great potential," Haas says. "When I'm looking at an 8,000 gallon tanker truck full of biodiesel, the pHLip Test can tell me if the fuel is out of spec. Since I can use it in real time, if a producer [or marketer] knows this is possible, it might eliminate some problems."

Alleman, who conducted NREL's 32-sample analysis, gives her opinion of the efficient field test. "Clearly no field test can be substituted for running the actual ASTM tests to confirm biodiesel quality," she says. "With that said, there is a need within the industry for rapid-screening tests for biodiesel quality. Our testing with a portion of the quality survey samples has shown that the pHLip Test successfully provided qualitative information on specific biodiesel quality parameters."

Measures can also be taken at the state level. "We saw a much lower failure rate in states with an active quality enforcement program," says McCormick, who specifies Iowa, Missouri and Minnesota as states with such programs. "I think it should be noted that all samples collected in Minnesota met the specification. I believe that this is because, after the problems that occurred last winter, all of the biodiesel blenders have begun to test every shipment that arrives at their terminals, rejecting shipments that do not meet the spec."

Ron Kotrba is a Biodiesel Magazine staff writer. Reach him at or (701) 746-8385.
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